The design of isopleth drawing and analyzing software based on VB for TV weather forecasting under the Windows environment is described. By using a modularized scheme, it has a succinct interface and is convenient to operate. The isopleth drawing of rectangular grids and the principles and techniques of adjusting isopleth control points are described in detail. The animated script files of isopleth drawing are generated with the fourth kind of grids from MICAPS data, and the process of weather development is displayed on the platform Weather 3D. The practice proved that the software runs stably and has good applicability and translatability.